Original scientific paper

Synthesis, Crystal Structures and Properties of New Chloroniobium Cluster Hydroxides with Co-ordinated and Non-coordinated OH- Groups. The Presence of H₃O₂ Intercluster Bridges

Nevenka Brničević ; Ruđer Bošković Institute, P. O. Box 1016, 10000 Zagreb, Croatia
Biserka Kojić-Prodić ; Ruđer Bošković Institute, P. O. Box 1016, 10000 Zagreb, Croatia
Marija Luić ; Ruđer Bošković Institute, P. O. Box 1016, 10000 Zagreb, Croatia
Aziz Kashta ; Ruđer Bošković Institute, P. O. Box 1016, 10000 Zagreb, Croatia
Pavica Planinić ; Ruđer Bošković Institute, P. O. Box 1016, 10000 Zagreb, Croatia
Robert E. McCarley ; Arnes Laboratory, USDOE and Department of Chemistry, Iowa State University, Ames, Iowa 50011, U.S.A.

Abstract

The isostructural, trigonal clusters of the composition [Nb6Cl12(H20)6](0H)2 l/4CH30H • 6H20 1 and [Nb6Cl12(H20)6](OH)2 -6H20 2 have been isolated from alkaline solutions of [NbgClj^]2* cluster in alcohol/water (1:3) in the presence of NMe^H, while the presence of NEt^H yielded NEt^NbeCl^Hjjf^e^IS^O 3. Compound 1 crystallizes in trigonal space group R3m with a = 21.166(5) A and c = 23.812(4) Å, y = 120°, U = 9238.6(3) Å3, Z = 12. Two ciystal- lographically independent cluster octahedra (I and II) have been found in the unit cell of 1 in the ratio 3:1. The Nb-0 distances of 2.211(11) Å and 2.217(16) Å for I and 2.238(19) Å for II indicate six co-ordinated water molecules. The cluster units of I are connected by hydrogen bonds of 2.49(1) A into a two-dimensional framework. Compound 3 is monoclinic, space group P2j/n, a = 10.085(5) A, b = 11.446(4) Å, c = 14.971(6) Å, /? = 102.95(6)°, U = 1684.2(1) Å3, Z = 2. The short Nb-O distances at 2.167(6), 2.177(8) and 2.187(7) A and considerable reduction of the Nb-O stretching frequency in the IR spectra support the presence of H302 (co-ordinated water molecule from one cluster unit and co-ordinated OH~ group from the neighbouring cluster unit) bridges. Each cluster unit is joined to the six neighbouring units by intermolecular hydrogen bonds of distances 2.540(11) Å and 2.594(10) Å in a three-dimensional network.

Keywords

Hrčak ID:

136698

URI

https://hrcak.srce.hr/136698

Publication date:

1.11.1995.

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